Article diverters and sorters utilizing a moving transport surface consisting of a plurality of parallel tubes have been known for a number of years. Such diverters and/or sorters having pushers mounted on tubes and cooperating with means to cause the pushers, on signal to move transversely across the transport surface and push the articles to one side or off the conveyor have been utilized for a number of years. Exemplary of this type of conveyor are U.S. Pat. No. 3,361,247, issued Jan. 2, 1968 to James N. Lauzon et al., U.S. Pat. No. 3,780,850, issued Dec. 25, 1973 to J. L. McSwiggin and U.S. Pat. No. 3,986,596, issued Oct. 19, 1976 to Dale R. Hamilton. It will be noted that a number of these patents involve sleeves which slide along the tubes and are big enough that the article rests on the sleeve and is thus transported transversely of the conveyor. However, more common is the arrangement disclosed in the Lauzon et al. patent, in which the articles are moved by pushers which project above the surface and are caused to move transversely of the conveyor as the transport surface progresses with one or more of the pushers engaging the article and pushing it to one side of the conveyor or completely off the conveyor surface. What disposal is made of the article so moved depends on the purpose of the equipment. This invention relates to the type of system which discharges the articles laterally from the transport surface.
Several problems have been encountered with these various prior art designs. Among these is the problem of warpage or bending of the tubes which gives them a slight arch along their length, thus, making them rotate somewhat eccentrically. Some of this bending occurs because the pushers twist about their vertical axes forcibly spreading the tubes apart. Such warpage or bending is often the result of the fact that such transport surfaces are wide and because of the nature of the structure, the tubes cannot be supported intermediate their ends without interfering with the lateral travel of the pushers. Such deflection or warpage may also occur as a result of the weight of the articles being transported on the transport surface. Whatever the cause is, the deflection or warpage causes the spacing between adjacent tubes to widened in some areas and significantly narrowed in other areas. To overcome this problem, that portion of the pushers, that is, the neck extending vertically between the tubes has to be made substantially narrower than would be the case if the tubes were all straight and uniform. Thus, the depending neck or leg which extends between the tubes has a loose or sloppy fit with the tubes, permitting the pusher to twist about its vertical axis in response to resistance of the articles on the transport surface to being moved transversely of the surface. Such twisting causes binding, excessive wear, and higher demands on the prime mover driving the transport surface. Further, it may cause improper contact between the pushers and the article.
Another problem which has been encountered in existing equipment of this type is the fact that when the system is used for heavy articles or articles having surfaces with a high coefficient of friction the resistance to being moved lengthwise of the tubes becomes great enough that the pushers are caused to tilt about a transverse axis with the lead or forward end of the pusher rising in response to the resistance of the article. This results in excessive wear and in substantially increased resistance to movement between the tubes and the pusher. In fact the upward force thus created may be sufficient to pivot the tubes supporting the pushers about one end, lifting the tubes and the chain at the other end. In some cases, this results in the guide pin or guide wheel which depends from the pusher and engages the guide rail beneath the transport surface to jump over this rail, thus, rendering the pusher nonfunctional. This, of course, results in a malfunction and significantly impairs the efficiency and dependability of the equipment. The rotational and lifting forces complement each other in creating serious malfunctions of the system.